Ductless Heating & Cooling

The Advantages of ENERGY STAR Certified Ductless Heat Pumps

Used for decades in Europe and Asia, “ductless” mini-split heat pumps differ from traditional home heating and cooling systems by:

• Providing both heating and cooling through a single device – a heat pump.¹  Heat pumps have been used, mainly in Southern climates, for decades. 
• Avoiding ductwork.  Instead of difficult-to-install, leaky and bulky ductwork, ductless mini-split heat pumps use an indoor unit² connected to an outdoor unit³ via refrigerant lines (which only need a three-inch hole in an outdoor wall for installation).  Up to 8 indoor units can be attached to one outdoor unit. (See Figure 1)

Figure 1. Ductless Mini Split Heat Pump

• Allowing for Different Climates for Each Room. Each indoor unit can provide customized heating and cooling -- adjustable through wall consoles, remote controls and smart phone apps -- in each conditioned space.
• Cutting heating costs in half compared to conventional electric heating systems.  Because they transfer instead of generate heat, ENERGY STAR certified ductless mini-split heat pumps use 60% less energy than standard home electric resistance-based heating systems. 
• Cutting cooling costs by 30% compared to conventional room air conditioners.  ENERGY STAR certified ductless min-split heat pumps use more sophisticated compressors and fans that can adjust speeds to save energy.   

Ductless mini split heat pump models that have earned the ENERGY STAR are identified in the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) online database.  (Check the “Yes” box in “Labeled ENERGY STAR” search criteria to see a list.)

Common Applications of Ductless Heat Pumps

Ductless mini split heat pumps are increasingly being used in these situations:

• Homes with costly electric heat (e.g., baseboard; furnace; wall heaters; electric radiant) that will also benefit from cooling.
• Older homes with no ductwork (e.g., radiators or baseboard heat) that never had central air conditioning before.
• Homes with expensive central heating systems due to high fuel costs or low system efficiency.
• Additions or outbuildings (e.g., shed, barn, garage) where extending ductwork or cooling/heating capacity is not feasible.
• Rooms that are not regularly occupied (indoor unit can be turned off to save money).
• Spaces adjacent to unconditioned spaces where ductwork would be exposed to harsher temperatures (e.g., a guest room above a garage).
• New construction of homes in areas with high fuel costs.   
• Older commercial buildings with no existing ductwork for air conditioning or expansions. 

Further Developments – Cold Climate Heating, Alternative Indoor Units

In the past, people worried whether heat pumps were good at providing heat in cold climates.  As temperatures drop, the heat pump must work harder and harder to extract heat from the outdoor air.  Some heat pumps now utilize advanced compressors and refrigerants that allow for improved low temperature performance.  If this is a concern, look for ENERGY STAR models with a Heating Seasonal Performance Factor (HSPF) of over 12.0 BTU/Wh⁴ or examine a list of ductless mini-split heat pumps designed to work in colder climates developed by the Northeast Energy Efficiency Partnership (NEEP).  

Another concern may be the aesthetics of the relatively large indoor floor or wall mounted units.  U.S. consumers, accustomed to having heating and cooling delivered from barely noticeable vents in walls and ceilings, can sometimes find the look of the indoor wall or floor mounted units unappealing.  Ductless system manufacturers offer ceiling-recessed and short-run horizontal, duct-based air handlers, to provide a look some U.S. homeowner are more comfortable with.

Utility Incentives Available

ENERGY STAR certified ductless heating and cooling systems are eligible for rebates from some local utilities -- up to $1,000 per unit depending on what system is being replaced.   A list of available rebates can be found here.